Using your hands is a bad idea. The heat from your hands will, in time, melt the butter making your biscuits less flaky. Besides, karate chopping butter is difficult to boot.
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Jake RobinsonOct 9 '12 at 18:49

3

@Jake- This technique has its place and isn't a bad idea. It is done with the fingertips to limit melting and is more of a rubbing motion. It is less flaky because some of the fat is rubbed in but sometimes that is desirable for a more tender product.
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SobachatinaOct 9 '12 at 20:04

One, cut up your butter into small cubes, then freeze it on a plate. The colder you keep the butter the better the result. Then, if you have one, use a food processor to cut the butter into the flour. I don't have one, so I use a cutter, then finish it with my fingertips. If I feel the butter is getting too warm I'll put the bowl in the freezer for a few minutes.

I've found that as important as the cutting is the flour I use. The lower the protein content the better. That, and work the dough as little as humanly possible to avoid gluten chains.